Sorry, it's not in the DIP menu like I thought, but I was able to get it working. I found this following information on the Rec.Games.Pinball newsgroup... This is actually regarding the actual machine, but it works for the VPM version as well.
Keys for VPM version:
7 = AUTO-UP MANUAL-DOWN
8 = ADVANCE
In the game adjustments menu, function 31 is for the sound option.
00 = background sound OFF (factory)
01 = Background sound ON.
To get to the game adjustment do the following:
1. In game over mode, and the coin door open,
2. Set the AUTO-UP MANUAL-DOWN to AUTO-UP,
3. Press the advance button once, 04 will appear in the credit window.
4. Press the advance button 31 more times and the number in the ball
in play window will scroll to "31" (function 31)
5. In the player one window the current value for the setting will be
shown.
6. Press the credit button once to change the player one value to 01
(background sound on).
7. Turn the machine off to "save" the setting.
8. Turn the machine on and background sound should be on
Depending on which ROM you have, this may help as well. For me it was setting 31 as described above which means the section below was not needed, though someone else may find it of use.
The setting depends on which ROM's you have installed in the CPU board.
If they are the newer green ROM's it's setting #31 set to 01 = on
IF their the older ROM's then it's setting #33 set to 01 = on.
Since this is all a bit tricky to translate to VP, exactly the keys that worked for me were:
8 8 7 8 8 8 8 (go slowly, waiting a second or two between each)
That should get you to 04 in the credit window and 00 in the ball in play window. Now, press 8 until the ball in play advances to 31 (or 33, see notes above). You should see 00 in the player 1 display. Press 1 (credit button) to advance that display to 01. Press F3 to reset VPM, which saves the change.
